This invention relates to manways used to cover the opening in tanks and allowing access to the interior of tanks; in particular, the invention relates to a device for protecting specific areas on the manway.
Tanker cars used to transport hazardous materials are subject to severe limitations due to standards imposed by various governing bodies, such as The Chlorine Institute and the American Association of Railroads. For instance, a valve must be attachable to the industry standard manway cover which covers the opening in the tanker railcar or other transport vehicles, such as a river tank barge or highway trailer tanker or ISO storage transport tanks (collectively, xe2x80x9ctankerxe2x80x9d). One standard manway has five openings for the attachment of four loading valves (two for liquids and two for gasses) and a pressure relief valve. Further, all five valves must fit within the confines of the protective dome covering, the manway. A more restrictive requirement is that each individual valve must be sized to fit within the confines of an emergency hood, generally a cylindrical space of height 13.5 inches with radius of 3 inches (for the loading valves). The emergency hood is a device for sealing one of the five valves attached to the manway in the event of a leaking valve. In this fashion, a leaking valve can be isolated without removing the tanker from service and without the need to remove the defective valve until the tanker is scheduled for maintenance. To be effective, the emergency hood must sealingly isolate the leaking valve. Currently, emergency hoods are cylindrically shaped with an opening at one end. On the open end is placed a gasket, which, when the hood is installed, rests against the surface of the manway cover. Downward pressure on the hood forces the gasket surface into sealing contact with manway cover surface. Unfortunately, the surface of the manway may have become pitted, etched or contain other such surface blemish due to exposure to weather, exposure to hazardous cargo, or physical abuse. Once surface blemishes develop in the area of the emergency hood sealing gasket, the hood sealing gasket may perform inadequately, that is, may not properly seal the leaking valve.
Due to the possibility of surface blemishes in the seal area, existing means of attaching the emergency hood must provide substantial downward force on the hood seal to attempt to isolate the surface blemishes. The current means of attaching an emergency hood are cumbersome and bulky.
A manway cover system used to cover an opening in a tank, the manway cover system having a manway with a top and a bottom surface, at least one valve mounting area on the top surface for mounting a valve thereon, and a hood contact area surrounding each valve mounting area. The hood contact area is that portion of the top surface of the manway to be contacted by an emergency hood if an emergency hood was installed. The system further includes a flange, the flange being attachable to the manway, the flange covering a portion of the hood contact area when so attached. The flange further has an opening therethrough adapted to allow attachment of the flange on the manway without removal of a valve when mounted on the valve mounting area. A gasket is interposed between the flange and the hood contact area, thereby protecting the hood contact area from the exterior elements. Also included is a new emergency hood, adapted to replace the flange and seal a leaking valve.
Accordingly, it is an object of the present invention to provide a manway cover system which protects the hood contact area on a manway from the exterior environment.
It is another object of the invention to provide a manway cover system which allows for an emergency hood to directly attach to a manway without the need for large downward forces.
It is another object of the invention to have a flange installed on a manway which can be removed without removing installed valves.